Eli5 How can canned meats like fish and chicken last years at room temperature when regularly packaged meats only last a few weeks refrigerated unless frozen?

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Eli5 How can canned meats like fish and chicken last years at room temperature when regularly packaged meats only last a few weeks refrigerated unless frozen?

In: Chemistry

9 Answers

Anonymous 0 Comments

You ever check out the series “modern marvels” on the history channel? They do some great episodes and one went over how military rations get cooked and sterilized in huge batches. They use a pressure cooker the size of a small tractor trailer.

Anonymous 0 Comments

When food is canned it gets a “12D-kill” – which means it’s heated at a high enough temperature and pressure to kill all microorganisms, including *Clostridium botulinum*, the most dangerous food borne pathogen. So the food inside the sealed can is essentially sterile, and the food will remain unchanged for months if not years in the can. Eventually chemical processes may make the food unpalatable- but that’s a quality, not a safety issue.
When meat is refrigerated it significantly slows microorganism growth – but – spoilage bacteria will grow, slowly. These cause off odors, sliminess etc. Also a significant food borne bacteria *Listeria monocytogenes* can still grow at refrigeration temperatures.

Anonymous 0 Comments

Bacteria needs a few things to grow. The canning process denies bacteria of some of these things while simultaneously sterilizing and totally sealing off contents.

Regularly packaged meats have some bacteria in them at relatively safe levels. Cooling the meat makes the bacteria grow very, very slowly, but it is still growing so you have to eat it before the bacteria eats away at the meat. Cooking kills the bacteria, which is why meat needs to reach a specific internal temperature to be safe.

Anonymous 0 Comments

Louis Pasteur would like to have a word with you. Canning basically sterilizes the food eliminating any bacteria and barring any bacterial activity it is shelf stable. Canned food basically has a lifetime based on the lifetime of the can it is in.

Note the canning process basically cooks the food to rid it of bacteria so while preserved it isn’t exactly fresh either. Can’t have your cake and eat it too.

Anonymous 0 Comments

Canned food will eventually go bad because metal rusts/degrades and eventually the seal is breached, even if not noticed. If you ever find a can that has been sitting for, say, 50 years, I wouldn’t trust it. Besides, by then the contents would likely have become quite disagreeable…

Anonymous 0 Comments

How does botulism develop in canned foods? Sorry, piggybacking this question off of OP.

Anonymous 0 Comments

The canning process heats the food to a safe temperature while also creating a vacuum and sealing out pathogens that could potentially get into the food. This creates an environment in which it is highly unlikely for harmful bacteria to grow, resulting in a more shelf stable food. Fresh meats are exposed to oxygen, which most harmful food-borne bacteria need in order to reproduce.

Anonymous 0 Comments

The process of canning includes a step after the vessel containing the food is sealed where the contents are heated above a temperature where bacteria can survive thus killing all the bacteria. Since it is sealed no new bacteria can get and cause the meat to spoil.

In contrast, refrigeration does not kill off all the bacteria. It merely slows their multiplication significantly so it takes a lot longer to go bad than at room temperature but it is in fact slowly becoming more infested with bacteria every second. It’s just kept below a level where it will hurt us for as long as possible.

Anonymous 0 Comments

Part of the canning process usually includes cooking in the can after it’s sealed, so that any bacteria inside is killed and there’s no way for more bacteria to get inside to spoil the food.